Orthokeratinized odontogenic cyst with calcification: A rare case report of a distinct entity.

Orthokeratinized odontogenic cyst (OOC) is a relatively rare odontogenic cyst, distinct from odontogenic keratocyst (OKC). In the 4th edition of WHO Classification of Head and Neck Tumors (2017), OOC has been included as a separate entity in the category of developmental odontogenic cysts. It presents as a unilocular radiolucent lesion in the posterior mandible and is frequently related to impacted teeth, thus mimicking dentigerous cyst. Due to low local aggressiveness and no association with nevoid basal cell carcinoma syndrome, it does not show tendency to recur. When compared to OKC, OOC exhibits substantial number of differences with respect to clinical, pathological and behavioral features and treatment modalities. Hence, recognizing OOC as unique lesion is mandatory to avoid unnecessary overtreatment. This paper aims to report a rare case of OOC associated with impacted tooth, showing calcifications and emphasizes its differences from OKC. Furthermore, the recent concepts about OKC and OOC are discussed.